Cavitation devices of the type disclosed by Griggs (U.S. Pat. Nos. 5,188,090, 5,385,298, and 5,957,122), Hudson et al U.S. Pat. No. 6,627,784, Wyszomerski U.S. Pat. No. 3,198,191, Selivanov U.S. Pat. No. 6,016,798, Thoma U.S. Pat. Nos. 7,089,886, 6,976,486, 6,959,669, 6,910,448, and 6,823,820, Costa et al U.S. Pat. No. 6,595,759, Giebeler et al U.S. Pat. Nos. 5,931,153 and 6,164,274, and Archibald et al U.S. Pat. No. 6,596,178 are designed to mix and heat fluids passing through them. A cavitation zone is formed between a rotating cylindrical or other surface and a conforming housing surface, the rotating surface containing numerous cavities. The cavitation effect achieved by the mini-violent turbulence in and around the cavities is known. The Griggs and Hudson et al cavitation devices described in the patents above, in particular, have been used successfully in commerce. However, some fluids are more challenging than others. Many applications require handling dense materials with throughput rates beyond the capabilities of the existing devices and methods.
I have found that the prior art designs and methods do not efficiently account for the fluid properties of the materials to be mixed, or efficiently direct the flow patterns within the devices in many mixing applications.
Combined fluids (a) having high viscosities, and/or (b) that are dense or heavy, and/or (c) that include high concentrations of solids, are often found not to be well mixed using a desired flow rate through the cavitation devices described in the above patents. Prior art devices and methods are not able to overcome the negative effects of viscous drag sometimes even as exerted by fluids having relatively low viscosities. Both the designs of the devices and the methods of using them are wasteful of energy and limit the potential of the cavitation phenomenon as applied to virtually any fluid or combination of fluids to be mixed.
Hudson et al U.S. Pat. No. 6,627,784 in particular introduces the materials to be mixed through two inlet ports directing the flow orthogonal to its rotor and removes it from the center of the single rotor's cylindrical periphery, in an attempt to balance the flow. This construction and method have been found to generate excessive drag, is wasteful of energy, and is incapable of achieving an acceptable mix at high fluid flow rates.